Thermostatic circuit-controlling device



Feb. 26 1924.

I J. H. DERBY THERMOSTATIC CIRCUIT CONTROLLING DEVICE Filed March 101921 Patented Feb. 26, 1924.

UNITED srarias JOHN H. DERBY, OF NEW YORK, N. Y.

THERMOSTATIC CIRCUIT-CONTROLLING DEVICE. v

Application filed March' IO, 1921. Serial No. 451,291.

7 '0 all whom it may concern:

Be it known that I, JOHN H. DERBY, a citizen of the United States,residing at New York city, N. Y., have invented certain new and usefulImprovements in Thermostatic Circuit-Controlling Devices,

of which the following is a clear, full, and exact description.

This invention relates to thermostatic means for controlling thestarting and stop ping of motion and particularly to thermostaticelectric circuit controlling means such, for example, as those employedin fire alarm and fire prevention systems.

A general object of the invention is to provide thermostatic means whichis positive in operation, which may readily be constructed to operatefor any desired predetermined temperature, which will have all parts soprotected that dirt, moisture and other things which might tend to clogor corrode the parts are effectively excluded and which will operatewith certainty even when left without inspection for many years.

A particular object of the invention is to utilize the expansibleproperties of some of the more readily expansible and not readilycongealable liquids for eflfecting through such expansion the operationof devices of the class described and particularly the operation ofcircuit controlling or circuit changing devices. Other objects andimportant features of the invention will appear from the followingdescription and claim when considered in connection with theaccompanying drawings in which- Fig. 1 is a vertical section through athermostatic electric controlling device embodying the presentinvention;

Fi 2 is a plan view of the device shown in Fig. 1 looking from below,and

'Fig. 3 is a section on the line 3-3-of Fig. 1.

In the illustrated embodiment of the invention the casing in which themovable arts are enclosed comprises a base 2 having perforated ears 4 bywhich it may be attached to the ceiling or other support for the device,this base having embedded there in and preferably molded therein at thetime of its formation hexagonal nuts 6 which are adapted to receive thethreaded ends of the screws 8 by which the circuit terminals 10 are heldin osition in the device. The base 2, as wel as the other parts of thecasing, is preferably formed of some insulating material such, forexample, as bakelite or condensite or other phenolic condensationproduct.

It will be noted that the screws 8 also serve to clamp upon the base 2 adisk 12 of similar material which is provided with screw threads uponits periphery and which has upon its under face recesses in which thebase portions of the circuit terminals 10 are confined by the screws 8,these recesses serving to prevent the terminals from moving out of theopposed relation in which they are shown in Fig. 1. The base 2 isslightly recessed in its end surface to receive the ends of wireclamping clips 14: of well known construction, these clips eachcomprising a hook 16 adapted to hook over a bared part of one of thecircuit wires 13 and 15, the wire being held against the hook by acooperating clamp member 18 which is slotted at 20 to allow the hook 16'to pass through it. The flat inner end of clip 14 is pressed against thenut 6 by the disk 12 when the screws 8 are turned into clampingrelationto the terminals 10, thus making an effective electricalconnection between the terminals 10 and the wires 13 and 15.

The disk 12 has a central opening 22 therethrough in which is guided thestem 24 of a frusto-conical circuit-closing member 26 having its lowerend somewhat con caved to fit upon the convex outer surface,

of a glass or quartz cell 28 containing the expansible liquid. The stem24 of the circuit closing member is preferably triangular in crosssection so that its surface which contacts with the walls of the opening22 is reduced to a minimum, the greatest cross sectional dimension ofthis stem being preferably somewhat less than the diameter of theopening 22. Between the frusto-conical member 26 and the disk 12 islocated a spring 30 which presses the member 26 into them far enoughapart to let this member pass between the ends 82.

A suitable liquid for filling the cell 28 is carbon. tetrachloride whichis readily expansible and which does not freeze at the temperatures towhich devices of this type would be subjected. As will be seen from aninspection of Fig. 1, the cell 28 is not completely filled with thecarbon tetrachlo ride, the amount of air space ll provided above theliquid being varied in accordance with the temperature at which it isdesired that the cell shall explode. It the cell is to explode at a lowtemperature the air space is obviously smaller than when the cell is toexplode at a higher temperature and when, therefore. room must beprovided for expansion of the liquid in the cell before the cellbursting tempeature is reached.

The cell 28 is supported in a suitable seat in an opening in the coverpart 36 of the casing, which is of a hollow hemispherical, shape and isthreaded upon the peripheral threads of the dish 12, thus effectivelyenclosing the terminals and the movable parts of the device. The openingis somewhat less in diameter than the diameter of the cell 28 wherebythe major portion of the cell is not exposed to the outer atmosphere.jitter assembling the whole structure is preferably covered with acoating of waterproof varnish.

From the foregoing description, the operation of the device will readilybe understood. The device being located at or near the ceiling of a roomin which a the may start, the hot air rising upward will heat the cell28, which may be made either of glass, quartz, or other material thatreadily conducts heat, and the liquid, such as carbon tetrachloride,which substantially fills the cell, will quickly expand and when heatedto the temperature at which it is desired that an alarm be sent, theexpansion of the liquid will cause the cell to be shattered. thusreleasing the circuit-closing member 26 which will be moved by itsspring into contact with the ends 32 of the terminals 10, thus sendingin an alarm or controlling release boxes, or otherwise aid in inpreventing the spread of the fire.

it will be obvious that the invention is not restricted to circuitclosing, nor to the particular embodiment of the invention herein shownand described.

l-Vhat I claim as new is:

A thermostatic electric circuit controlling device comprising a quartzcell substantially filled with carbon tetrachloride, electric circuitterminals, a circuit closing member spring-pressed toward circuitclosing relation to said terminals, and a support for said cell arrangedto cause said cell to maintain said circuit closing member out ofcircuit closing relation to said terminal.

Signed at New York city, N. Y. this 7th day bf March 1921.

JOHN H. DERBY.

